# [ICEM] Element sizing question

 Register Blogs Members List Search Today's Posts Mark Forums Read

 July 23, 2009, 05:24 [ICEM] Element sizing question #1 Senior Member   Stuart Join Date: Jul 2009 Location: Portsmouth, England Posts: 484 Rep Power: 15 Hi, In the ICEM v12.0 Help Manual (page 234) it says "It is recommended that the Max Element value is a power of 2." So this must be 1/4, 1/2, 1, 2, 4 etc. But can the element sizes on Parts, Curves, Surfaces, Densities etc be defined as any value with a unit (such as 0.3mm, 0.1m etc)? Particularly needed when making the prism layer based on a first layer y+ calculation. I cannot find the answer in the Guide or anywhere to define the units I want to work in or that the imported geometry was created in, unlike in ANSYS Meshing. Therefore, I'm not 100% sure that the element sizes I want are being applied. BTW, I have not choice but to use ICEM as I need the mesh for the CFX replay remeshing. Thanks

 July 27, 2009, 02:21 #3 Senior Member   Stuart Join Date: Jul 2009 Location: Portsmouth, England Posts: 484 Rep Power: 15 Thanks Simon for the explaination. So if I wanted to have a prism layer and I know the first layer height in some unit (i.e. mm) based on y+, the number of layers needed and the layer height expansion factor. Therefore, I can calc the entire prism layer height in mm. How would this be correctly applied to an ICEM mesh? My guess would be to create a single prism layer to begin with that's equal to the total height and then, after getting a good quality surround tetra mesh, split the prism layer into the required number of layers with the required expansion rate.

 July 27, 2009, 08:44 Prism Inflation #4 Retired from CFD Online     Simon Pereira Join Date: Mar 2009 Location: Ann Arbor, MI Posts: 2,660 Blog Entries: 1 Rep Power: 38 Ok, to be clear, this powers of 2 stuff is for octree subdivision and does not apply to prism inflation… This is now a new subject. When running ICEM CFD prism, the most time consuming part is the smoothing and mesh adjustments that happen after each layer of prism is grown into the volume. So, if you need to grow 21 layers, it will take considerably longer than growing one layer to that same total height. Some ICEM CFD users swear by growing a single layer and then subdividing it as the quickest and best way… However, all that smoothing is actually doing something in terms of improving prism quality and dealing with difficult geometries, adjusting the prism growth directions, etc. After all, the code was designed expecting you to put in the total number of layers. If your model is simple enough and the single layer method works for you, then that is great. I often try a middle ground approach of starting with 3 or 7 layers (in this example). This provides a number of rounds of smoothing to get a somewhat advanced layer, but without waiting thru 21 layers. The easiest way for setup is to go to the Global prism settings and put in the number of layers you want (in this case, 21) and then set your initial height and ratio. It will calculate your total height. Then delete the initial height, put in your new number of layers (let’s say 7) and then hit calculate to get your new initial height. Run Prism like this, then use Split Prisms to split each layer into three and then redistribute prism with the initial height set back to what you wanted in the first place. If you have lots of surface size variations in your model, then perhaps just set ratio and number of layers. Leave total height and initial height blank. This will leave the initial height free to "float" so that the volume transitions between the last prism and outer volume are smoother. You can still redistribute at the end to get the exact initial height you wanted. If you do this well, you may still get a nice smooth transition even after subdivision and redistribution. Use 12.0 or 12.1 to get the more recent algorithms (a lot of work was done here at 12.0 and then even more for 12.1). You can use max height over base with an initial height to a similar end...

 January 22, 2015, 10:11 Why icem prompts "An application(prism)is currently running"? #5 Member   wanghuo Join Date: Aug 2014 Posts: 77 Rep Power: 4 hello friends！ I use icem to mesh the BCL .When I modify it ,the icem prompts "An application(prism)is currently running" That is why?Thank you?

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post niklas OpenFOAM 2 July 31, 2013 16:03 lian CFX 0 March 21, 2008 16:22 Bob CFX 5 February 17, 2004 01:04 Carlos Main CFD Forum 2 September 21, 2002 09:31 K.L.Huang CD-adapco 1 March 29, 2000 04:57

All times are GMT -4. The time now is 20:42.